BRIEF [O.A.] Klaatsch, Hermann Author: Klaatsch, Hermann Recipient: Haeckel, Ernst Dating: 07.11.1889
BRIEF [O.A.] Friedrich, Josephine Author: Friedrich, Josephine Recipient: Haeckel, Ernst Dating: 13.05.1876
BRIEF [O.A.] Friedrich, Josephine Author: Friedrich, Josephine Recipient: Haeckel, Ernst Dating: 19.03.1876
BRIEF [O.A.] Eylmer, Heinrich Author: Eylmer, Heinrich Recipient: Haeckel, Ernst Corporation: Universitäts-Frauenklinik Dating: 15.02.1918